FACTORS AFFECTING DELIVERY OF HIGH-EFFICIENCY DIALYSIS USING TEMPORARY VASCULAR ACCESS

The effectiveness of hemodialysis depends, in part, on the delivery of the prescribed rate of blood flow and the amount of blood recirculation. Studies evaluating the magnitude of recirculation in double-lumen catheters at blood flow rates ≥300 mL/min have not been performed. We therefore examined the effects of prescribed blood flow rate and placement site on measured blood flow, recirculation and effective clearance using double-lumen catheters in 17 patients. Double-lumen catheters were placed in the internal jugular (12.5 cm), subclavian (20 cm), and femoral veins (15 cm and 24 cm). Recirculation studies were performed in triplicate with a two-needle method at blood flow rates of 250, 300, 350, and 400 mL/min. Blood flow rate was measured with an ultrasonic flow meter placed on the venous line. The arterial line pressure was continuously monitored. Mean arterial line pressure was −105 ± mm Hg at 250 mL/min and −231 ± mm Hg at 400 mL/min prescribed blood flow rates in the internal jugular, subclavian, and 15-cm femoral vein catheters. Patients with 24-cm femoral catheters had a mean arterial line pressure of −196 ± mm Hg at 250 mL/min and −327 ± mm Hg at 400 mL/min. In spite of the change in arterial line pressure, measured blood flow rate increased appropriately at all set blood flows and with all catheter sites studied. Recirculation was low in the internal jugular, subclavian, and 24-cm femoral catheters (4% ± 1%9 5% ± 2%, and 10% ± 3%, respectively) at a set blood flow of 250 mL/min and did not increase at blood flow rates up to 400 mL/min. In contrast, recirculation with the 15-cm femoral catheters was 18% ± 7% at 250 mL/min and increased to 38% ± 14% at 400 mL/min. In five of six patients, the increase of recirculation with higher blood flow rates led to no change or to an actual decrease in effective clearance. This study suggests that it is possible to deliver high-efficiency dialysis through temporary vascular access placed in the internal jugular and subclavian veins. On the other hand, larger amounts of recirculation in the 15-cm femoral catheters led to a failure of high blood flow rates to enhance dialysis efficiency. © 1993, National Kidney Foundation. All rights reserved. All rights reserved.